As well known, the stability assessment of turbomachines is strongly related to internal sealing components. For instance, labyrinth seals are widely used in compressors, steam, and gas turbines and pumps to control the clearance leakage between rotating and stationary parts, owing to their simplicity, reliability, and tolerance to large thermal and pressure variations. Labyrinth seals working principle consists of reducing the leakage by imposing tortuous passages to the fluid that are effective on dissipating the kinetic energy of the fluid from high-pressure regions to low-pressure regions. Conversely, labyrinth seals could lead to dynamics issues. Therefore, an accurate estimation of their dynamic behavior is very important. In this paper, the experimental results of a long-staggered labyrinth seal will be presented. The results in terms of rotordynamic coefficients and leakage will be discussed as well as the critical assessment of the experimental measurements. Eventually, the experimental data are compared to the numerical results obtained with the new bulk-flow model (BFM) introduced in this paper.